MP4 to WebM Converter
Turn MP4 videos into WebM, the open web video format that browsers play natively. Free, with no account and no watermark.
Output: WebM with VP9 video and Opus audio, the standard combination for the web.
Need more changes? Continue in the full editor after downloading or processing the converted file.
How to convert MP4 to WebM
The converter re-encodes the video into VP9 and the audio into Opus and saves them as a WebM file. You do not need to choose a codec, quality or resolution.
Step-by-step
- Choose an MP4 file or drag it onto the upload area.
- Wait for the upload to finish, then click Convert to WebM.
- Wait while the video is converted. Encoding to WebM takes longer than to MP4, especially for long or 4K videos.
- Download the WebM and add it to your website, app or project.
What you get
The result is a standard WebM file built for the web:
- VP9 video with 8-bit 4:2:0 color, which Chrome, Edge, Firefox, Opera and current Safari play without plugins.
- Opus audio, the efficient open audio codec used by WebM.
- A file that is often smaller than the MP4 at similar quality, because VP9 compresses more efficiently than H.264.
- The original resolution and frame rate. An odd width or height is rounded down by one pixel, because 4:2:0 color needs even dimensions.
- HDR video converted to standard dynamic range, so colors look right on regular screens and in every browser.
Why use WebM?
WebM is an open, royalty-free video format made for the web. Browsers decode it natively, and VP9 needs less data than H.264 for the same picture, so pages load video faster and use less bandwidth. That is why many websites, web apps and online editors prefer WebM for background videos, animations and previews.
Outside the browser, MP4 is still the safer choice: phones, TVs, video editors and social apps support it more widely. Convert to WebM when the video is meant for a web page or for software that asks for WebM, and keep the MP4 for everything else.
MP4 and WebM: what is the difference?
Both are containers. MP4 usually holds H.264 or HEVC video with AAC audio, codecs that are covered by patents and supported by almost every device. WebM holds VP8, VP9 or AV1 video with Vorbis or Opus audio, open codecs developed for the web.
Since WebM and MP4 normally use different codecs, renaming a file does not convert it. The video and audio have to be re-encoded, which is what this converter does. Each re-encode loses a little quality, so convert from the best MP4 you have.
Using WebM on a website
Current versions of Chrome, Edge, Firefox and Safari play WebM with VP9, but older iPhones and Macs may not. The reliable approach is to give the video element two sources: the WebM first and the MP4 as a fallback. Each browser plays the first format it supports, and visitors on older devices still see the MP4.
For a background or hero video, keep it short, remove the sound if it is not needed, and check the file size after converting. A few seconds of looping video should weigh no more than a few megabytes, so the page still loads quickly on mobile connections.
When to convert MP4 to WebM
Convert when the video is meant for the web or for software that expects WebM:
- Adding a background, hero or product video to a website or landing page.
- Embedding video in a web app, browser game, online course or HTML presentation.
- Uploading to a platform, CMS or tool that requires WebM.
- Making a lighter copy of a clip for browser playback while keeping the original MP4.
Quality, file size and limits
The WebM is often smaller than the MP4, but not always: if the MP4 was already strongly compressed, the sizes can be similar.
Files can be up to 200 MB. VP9 encoding takes noticeably longer than H.264, so a long video can take several minutes to convert. The WebM is opaque: this converter does not create or keep transparency, and an ordinary MP4 has none to begin with.
Compress, trim or convert the video
WebM to MP4 Converter
Turn a WebM recording or web video into an MP4 that plays almost everywhere.
Compress Video
Make the MP4 smaller instead, if you need a light file that plays everywhere.
Trim Video
Cut a short clip for a background or preview video before converting.
Convert Video Format
Choose MOV, MKV, AVI or another output format instead of WebM.
Need to Edit Your Video?
Continue with trimming, resizing, cropping, text, subtitles, audio, and other edits in the full editor.
Learn more about WebM and MP4
Frequently Asked Questions
Common questions about converting MP4 files to WebM.
Is the MP4 to WebM converter free?
Yes. It is free, you do not need an account, and the WebM has no watermark.
Will converting MP4 to WebM reduce quality?
The video is re-encoded, so it is not lossless, but the settings keep the original resolution and frame rate and aim to keep the difference hard to see. Convert from the original MP4 rather than from a copy that has already been compressed.
Is WebM smaller than MP4?
Often, yes. VP9 compresses more efficiently than H.264, so a WebM at similar quality usually needs less data. If the MP4 was already heavily compressed, the difference can be small.
Will a WebM play on an iPhone or Mac?
In current Safari, yes, but older iPhones and Macs may not play it, and the Photos app does not handle WebM well. On a website, offer an MP4 fallback next to the WebM. To share a video directly with someone, MP4 is the safer choice.
Why does converting to WebM take longer than to MP4?
The VP9 encoder spends more time per frame to reach its better compression. A short clip converts quickly, but long or 4K videos can take several minutes.
Is there a file size limit?
Yes, files can be up to 200 MB. For a website, shorter clips are better anyway: trim the video to the part you need before converting.